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NAC is an incredible antioxidant with numerous health benefits. It may help with mood disorders, sleep, infections, and inflammation. NAC protects the brain, gut, kidneys, liver, and lungs. It helps with most states of increased oxidative stress, which underlie chronic health problems. We list and describe all the benefits of NAC, along with dosage and side effects.

What Is NAC?

NAC is short for N-Acetylcysteine. NAC is transformed into cysteine in the body. Cysteine is the most important amino acid that makes glutathione, the body’s strongest antioxidant [R].

Cysteine levels determine how fast glutathione is made, NAC is essential in replenishing levels of this antioxidant in the body. Glutathione removes free radicals from cells and activates detox pathways [R, R].

NAC also falls under the category of “thiols”, antioxidant substances that contain the sulfur group. NAC is a thiol thanks to the sulfur-containing cysteine. In fact, this sulfur in cysteine is essential for the antioxidant activity of glutathione [R].

NAC can directly fight free radicals, acting as a powerful antioxidant [R].

Its antioxidant effects protect DNA, cells, tissues, and organs from damage, inflammation, and harmful substances [R].

NAC can also break down and soften mucus, which can improve lung diseases [R].

NAC has been thoroughly researched. The number of clinical, animal, and cell studies that explored the benefits of NAC are almost impossible to list. Close to a thousand clinical trials of NAC exist alone!

NAC Snapshot

Pros

  • Good for protecting the lungs, gut, brain, liver, and kidneys
  • Protects from many toxins and pollutants
  • Helps with obsessive-compulsive symptoms and addiction
  • Helps prevent the flu
  • Powerful antioxidant
  • Increases the master antioxidant Glutathione
  • Great biofilm disruptor
  • Improves fertility
  • Good for many chronic health problems

Cons

  • Doesn’t taste good and can cause a bit of nausea
  • May affect bleeding

Health Benefits of N-Acetyl Cysteine

1) NAC Protects the Liver

NAC boosts the antioxidant glutathione, the highest amount of which is in the liver. This helps explain why NAC has such a strong effect on protecting the liver from inflammation, drug poisoning, and serious liver diseases.

Liver inflammation

If the liver is damaged by any factor, inflammation and oxidative stress always rise. NAC can protect the liver by reducing inflammation and increasing antioxidant reserves.

NAC reduced liver damage in 85% of all cases, according to a review of 68 pre-clinical and 1 clinical study. It could protect the liver from factors such as excessive alcohol or environmental pollutants [R].

NAC helped increase liver function better than glutathione in one study of 75 patients with Hepatitis B. The patients received very high doses of NAC (8 g/day) as injections for almost a month [R].

Acetaminophen poisoning

N-Acetyl Cysteine has been used as an antidote to acetaminophen poisoning for over 50 years. Commonly-used painkillers (such as Tylenol and Vicodin) contain acetaminophen, which can damage the liver and even cause liver failure in high doses. It’s the most common cause of serious, sudden, liver damage [R, R].

N-Acetyl Cysteine is the most effective drug that can prevent serious liver damage from acetaminophen and increase survival, according to several studies of over 400 patients. NAC also has very few side effects [R, R].

Serious Liver Damage

Sudden, life-threatening liver damage can rarely also be caused by factors other than acetaminophen: various drugs, toxins, or hepatitis.

NAC helped protect the liver in 80 such cases (RCT), increased their survival and shortened their hospital stay. The patients with liver damage from drugs experienced the best results [R].

NAC has been studied a lot in the intensive care units, as a possible way to reduce organ damage before and after surgery. It helped protect the liver in 70 patients with lung disease, given shortly before heart surgery. 900 mg/day of NAC was given for a week [R].

NAC also reduced liver damage when given shortly before liver surgery in a study of 48 people (DB-RCT) [R].

2) NAC Fights Free Radicals

Oxidative stress can damage cells and is increased in many chronic diseases, malnutrition, and toxin exposure.

NAC can replenish glutathione, protecting cells and organs that are under oxidative attack [R].

In several studies of 43 healthy men in total (RCTs), 1,200 mg of oral NAC daily increased antioxidant status after just 8 days. It increased the levels and activity of glutathione enzymes and reduced oxidative damage markers by more than 30%. NAC could also increase red blood cells and markers of their function and size (erythropoietin, hemoglobin, hematocrit, MCV) [R, R]

Oral glutathione has poor bioavailability, and taking NAC is one way to circumvent this. Oral NAC (200 mg of power/day) increased glutathione and antioxidants better than oral glutathione in a study of 20 people. But sublingual glutathione had stronger effects than both NAC and oral glutathione after 3 weeks [R].

In African countries, children with severe malnutrition do not have good chances for survival. NAC could increase their recovery and survival by raising their glutathione levels in a pilot study. These children received up to 1,200 mg NAC/day in addition to standard treatment. Since NAC is cheap and safe option to aid their recovery by boosting antioxidant levels [R].

3) NAC Reduces High Homocysteine and Heart Disease Risk

B vitamins only somewhat help reduce high homocysteine, while NAC can lower both homocysteine and high blood pressure. Normalizing homocysteine could help prevent heart disease and other chronic health problems [R].

In two studies of 82 men in total (DB-RCTs), oral NAC (1,800 mg/day) lowered homocysteine and blood pressure while increasing antioxidant status over 4 weeks. It had an equally beneficial effect in men with high and normal blood lipids, and in both smokers and non-smokers [R].

In another study of 60 people with heart disease, NAC (600 mg/day) lowered homocysteine levels and improved blood vessel health over 2 months [R].

4) NAC Protects from Toxins and Pollutants

Glutathione is not stored only in the liver. By increasing levels of glutathione throughout the body and combating oxidative stress, NAC can protect from many toxins and pollutants.

Heavy Metal Exposure

NAC may be a safe alternative for chronic lead toxicity.

NAC reduced lead levels, increased glutathione and antioxidant enzymes in red and white blood cells in 171 workers exposed to lead after 3 months. It reduced both lead levels and homocysteine The beneficial daily dose was 400-800 mg per day [R, R].

The combination of NAC and zinc could also protect from mercury toxicity in rats, preventing the accumulation of mercury in the liver and blood [R].

Pesticides

NAC could help with pesticide poisoning by increasing glutathione and antioxidants, which helps the body and affected organs detox. NAC given to 30 people suffering from pesticide poisoning increased glutathione and reduced the need for additional treatments (RCT). Everyone received 1,200 mg NAC/day for only 3 days [R, R].

NAC also reduced the damage from a very toxic pesticide (aluminum phosphide) in one study (RCT). It reduced the hospital stay, improved breathing, and increased survival in those exposed to these pesticides [R].

Diesel Fuel

Exposure to diesel fuel can cause serious blood vessel damage, even in healthy people.

Taking NAC with vitamin C before diesel fuel exposure protected the blood vessels in one study of 21 people (DB-RCT). They took 1,200 mg of NAC the day before being exposed to diesel, and 1g of vitamin C daily for a week [R].

Diesel fumes can also cause breathing problems and worsen asthma. NAC (1,800 mg/day) over 6 days protected the airways and improved asthmatic symptoms in 26 people exposed to diesel (DB-RCT). It could reduce the need for asthma medications in this population [R].

Silica

Silica is often found on construction sites and in agriculture. It can cause serious lung damage. In 96 people exposed to silica, NAC (1,200 mg/day) combined with an anti-inflammatory improved lung function, coughing, pain, and congestion [R].

Chemical Warfare

NAC (1,200 mg/day) improved breathing, cough, congestion, and lung function in 144 people with poisoning from a chemical warfare agent (mustard gas). It was given over 4 months and had a very beneficial effect on oxidative stress (DB-CT) [R].

Deadly Mushrooms

NAC can be a lifesaver when it comes to poisoning from Death Cap, the number one cause of fatal mushroom poisoning worldwide. NAC added to the anti-poisoning protocol enabled people to recover from the poisoning and prevent liver failure [R].

5) NAC Improves Lung Disease

COPD

NAC is commonly used to reduce the inflammation and mucus in people with lung disease, such as chronic bronchitis or Chronic Obstructive Pulmonary Disease (COPD). It can break down mucus and replenish glutathione in the lungs, which reduces airway damage and breathing difficulties [R].

In a review of 39 human studies, NAC can improve symptoms and prevent disease worsening in chronic bronchitis with no side effects. It needs to be taken for at least 3-6 months to achieve the respiratory benefits. Only 2 months of NAC, for example, did not improve COPD in one study of 51 people [R, R].

NAC combined with vitamin C increased the antioxidant and nutritional status in 79 people with COPD (RCT)[R].

Even high doses of NAC (1,200 mg/day) given over 1 year were safe in a study of 120 COPD patients. NAC improved lung capacity, breathing, and prevented worsening [R].

NAC can also be given alongside oxygen, the typical COPD treatment. In 45 patients, it could prevent oxidative damage that can result from long-term oxygen treatment. NAC was given at the same time as oxygen at up to 1,800 mg/day for 3 days [R].

NAC could preserve lung function in 82 COPD patients who had to undergo heart surgery (DB-RCT) [R].

Lung Damage and Infections

NAC had mixed effects on lung damage in two studies of 151 patients with a lung-scarring disease. In a smaller study of 28 patients, inhaled NAC could help those with milder forms of the disease. Oral NAC did not have the same benefits in the larger study [R, R].

Short-term, NAC (2400 mg/day) increased the level of vitamin C and antioxidant status in patients with a lung infection and scarring but didn’t improve lung function. It was given only for 30 days, which is probably not long enough to impact tissue regeneration [R]

Inhaled NAC could also help with airway infections in a study of 100 small children [R].

6) NAC May Help Fight the Flu

Since NAC decreases the body’s inflammatory response, it may help prevent the flu or reduce symptoms of the common cold.

In one study of 262 older people, those adults taking NAC only developed the flu 25% of the time while those not taking NAC developed the flu 79% of the time. NAC could be especially helpful in the winter months when the flu season takes a hold [R].

NAC is also sometimes added on to standard treatments of sinus inflammation and infections, although the benefits are uncertain [R, R].

In cells, NAC reduced replication of the flu virus. If the virus can’t replicate quickly, it’s easier to fight it off. [R].

7) NAC May Help Fight Addiction

It was first discovered that NAC has the potential for helping combat various types of addiction in animals. It could reduce binge eating in rats [R].

Cysteine from NAC seems to be able to enter the brain and normalize the neurotransmitter glutamate. Glutamate affects reward pathways involved in addiction, and NAC is able to re-balance its levels [R, R].

A large review of 165 patients and 9 studies found NAC especially useful for cannabis and cocaine addiction. NAC could also help with nicotine dependence, methamphetamine addiction, and pathological gambling [R].

It seems to also help some odd types of impulsive behaviors, such as hair pulling. NAC (1200-2400 mg/day) could reduce uncontrolled hair pulling in a study of 50 people with no side effects (DB-RCT) [R].

Veterans with PTSD and addictions did a lot better after 8 weeks of NAC (2,400 mg/day) and psychotherapy (DB-RCT). NAC reduced overall symptoms, craving, and depression in all 35 veterans who participated [R].

Amphetamines

NAC helped reduce craving in 23 people with methamphetamine addiction (DB-RCT). They received 1200 mg/day NAC for 4 weeks [R].

But in another study (DB-RCT), NAC combined with an opioid blocker (naltrexone) did not show any benefits in 31 people with methamphetamine addiction [R].

Cocaine

When it comes to cocaine dependence, NAC may help reduce craving and relapse.

In one study of 111 people, NAC helped maintain abstinence from cocaine taken at 2,400 mg/day for 8 weeks (DB-RCT) [R].

NAC also helped reduce cocaine desire in 15 people after just 3 days (DB-CT) [R].

When 8 people with cocaine dependence were given NAC (2400 mg) and taken to a brain scanner, their brain glutamate levels went down. NAC didn’t have this effect in 14 healthy people under the same conditions. This suggests that NAC can specifically lower abnormally increased glutamate in people with addiction [R].

Cannabis

People addicted to cannabis who try to quit often revert to overdrinking. In 302 people addicted to cannabis (DB-RCT), NAC could reduce alcohol consumption by 30% in those trying to quit. They used a higher dose of 2,400 mg NAC/day for 3 months [R].

In another study, however, NAC had no effect on cannabis addiction in adults [R].

Women heavily dependant on cannabis tend to have more problems quitting and experience mental health struggles. This is why NAC may only affect men, whereas women would need additional treatment for low mood and anxiety [R].

In 116 marijuana-dependant teenagers (RCT), those taking NAC at 2,400 mg/day used less marijuana and alcohol. Since NAC is very safe, it could be helpful for adolescents suffering from alcohol and cannabis overuse [R].

Several studies are still exploring the effects on NAC on cannabis addiction [R].

Nicotine

One study on almost 100 people confirmed that smokers have higher brain glutamate levels [R].

In 16 smokers, NAC (2,400 mg/day) helped maintain abstinence and reduce craving (DB-RCT). Brain scanned showed that NAC could help restructure the circuitry in the brain’s reward pathways after just 4 days [R].

NAC reduced the number of cigarettes smoked in 35 people after 3 months. Almost half of the people who took NAC quit smoking, while only one-fifth of the placebo group did [R].

One study used 3,600 mg of NAC daily for 4 days in 10 people, while 12 got a placebo (DB-RCT). NAC slightly reduced withdrawal symptoms. Smokers also rated their first cigarette after NAC as less enjoyable [R].

Gambling

NAC increased the long-term benefits of psychotherapy in a 3-month study of 28 gamblers who also smoke. It could also reduce pathological gambling in 27 people after 2 months (open-label). They used typical doses, about 1,500 mg/day [R, R].

8) NAC May Improve Depression

NAC may be able to help people with depression by balancing brain glutamate levels, reducing inflammation and increasing new brain cells [R, R].

In a review of over 500 people (SR of 5 studies), NAC could improve symptoms of depression and overall functioning after 3-6 months [R].

NAC (2000 mg/day) improved mood in people with depression after 3 months [R].

In another study, NAC had to be used for at least 4 months to improve depression (DB-RCT) [R]. In a study of 76 depressed patients (DB-RCT), those who took NAC had higher brain antioxidant levels [R].

9) NAC May Help with Bipolar Disorder and Mania

NAC could improve chronic health issues, such as heart disease and hormonal imbalance, in people with Bipolar Disorder (RCT). NAC had an indirect effect in this 6-month study, affecting overall health, antioxidant status, and inflammation more than mood [R].

In another study with 17 bipolar patients (RCT), NAC improved low mood and overall symptoms after 6 months [R].

Larger studies are currently underway to confirm the benefits of NAC for Bipolar Disorder [R].

NAC could also improve mania symptoms in a small study of 15 people after 6 months (RCT). The NAC group experienced less mania, while the placebo group did not improve and even experienced mood worsening [R].

10) NAC Improves Obsessive Compulsive Disorder (OCD)

NAC may help with OCD by balancing glutamate and increasing antioxidants in the brain. In a study of 44 OCD patients, NAC (2000 mg daily) as an add-on to standard medications improved symptoms even in severe OCD [R].

In a study of 48 OCD patients who previously didn’t respond to drugs (DB-RCT), NAC could safely improve symptoms after 3 months [R].

Some studies, however, didn’t find benefits to NAC for OCD [R].

Although inconsistent, NAC can still be considered useful for obsessive-compulsive disorders according to a large review. It shows some promising benefits and has very few side-effects [R].

11) NAC Improves Polycystic Ovary Syndrome (PCOS)

Clomiphene citrate is considered the gold standard for helping women with PCOS achieve ovulation. But more than half of women don’t respond to it. NAC is being researched as a potential alternative, although the studies so far have mixed results [R].

In the largest study of NAC in 150 women with PCOS who previously didn’t respond to treatments (DB-RCT), NAC added to clomiphene citrate improved the ovulation and pregnancy rates after just 5 days. This was confirmed in another study of over 100 women (RCT) [R, R].

In another study of 60 women with PCOS (RCT), NAC improved the quality of egg cells (oocytes). It also increased embryo health during in vitro fertilization [R].

Women with PCOS often suffer from weight gain. NAC could improve metabolic symptoms in 46 women with PCOS (DB-RCT), helping to reduce blood lipids, fasting glucose and insulin better than metformin (an anti-diabetic) [R].

NAC had similar benefits to metformin in a study of 100 women with PCOS (RCT). It reduced high testosterone, high insulin, irregular menstruation, and BMI after 6 months. Unlike metformin, NAC also lowered total and LDL cholesterol. NAC improved insulin sensitivity in another study of 31 women with PCOS over 5-6 weeks [R, R].

NAC was dosed at 1,200-1,800 mg/day in the above studies.

NAC alone did not have any benefits in some other studies of women with hard-to-treat PCOS. It possibly works better when combined with the standard drugs than when used just by itself [R].

12) NAC Improves Male Fertility

Aside from potentially helping women with PCOS, antioxidant therapies like NAC may help increase fertility in men [R].

Oxidative stress can damage the sperm’s DNA, which reduces fertility [R].

In 120 infertile men (RCT), NAC improved semen quality and antioxidant status after 3 months [R].

Some studies looked at the fertility benefits of NAC with other antioxidants, such as B vitamins, vitamin C and D. This combination improved the sperm count in those with low sperm count in a study of 42 men (RCT) [R].

In a large study of almost 500 infertile men, NAC with selenium improved semen quality after 6 months [R].

Some men are “subfertile” — they’re less fertile, but an obvious cause doesn’t exist. In 84 such men trying to conceive with their partners, a NAC supplement combination (called Condensyl, with vitamins, zinc, fig extract, and vitamin E) increased pregnancy rates. It increased the “fertility potential” of these men, making a successful pregnancy more likely [R].

The typical NAC dose for improving fertility in these studies was 600 mg/day. Multi-compound antioxidant supplements can contain less NAC.

13) NAC May Help Sleep Apnea

NAC improved sleep, reduced apnea and snoring in one study of 20 people with Obstructive Sleep Apnea after a month (OSA) (RCT). Long-term, it may reduce the need for continuous positive airway pressure therapy [R].

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14) NAC May Boost Skin Health

NAC can also be used as a cream or gel to improve skin health. It can boost glutathione in the skin, protecting it from damage. NAC can also reduce skin inflammation and normalize skin cell division. It has been used for eczema, skin irritation, radiation-induced skin damage, wound healing, and acne.

In one study of 100 people (DB-RCT), a 5% NAC gel helped reduce mild to moderate acne [R].

Case reports and animal studies support this wide range of skin benefits of NAC. Overall, NAC skin formulations are promising and very safe, although larger studies are harder to come across [R].

15) NAC Reduces Chemotherapy Side Effects

NAC could prevent from chemotherapy or x-ray scanner side effects due to its antioxidant action. It can be safely used as an infusion, injection, or orally.

Cisplatin is a common chemotherapy that can damage the ears and kidneys. NAC ear injections prevented cisplatin damage and protected the ears in a study of 84 people [R].

NAC infusions could also reduce mouth ulcers and inflammation from chemotherapy in a study of 80 people with leukemia (DB-RCT) [R].

In a pilot study, oral NAC (1,200 mg/day) protected from the side effects of chemotherapy on the brain in 14 people with colon cancer [R].

NAC and other antioxidants may prevent from x-ray radiation used to diagnose bone cancers. A NAC combination (1,200 mg NAC, 2g vitamin C, 600 mg lipoic acid, 30 mg beta-carotene) protected 5 people from x-ray scanner damage in one study [R].

One study determined that even high very doses of NAC were safe in 28 people with kidney damage, which chemotherapy can cause. They used 450 mg per kg/2 lbs through an IV, which would be over 20 g of NAC for a person weighing 110 pounds [R].

16) NAC Protects the Ears

Interestingly, NAC may even protect the ears from hearing loss caused by loud music or sound damage.

NAC helped 35 people regain hearing after experiencing sudden deafness. In almost 600 soldiers who were at high risk for hearing loss, NAC slightly reduced ear damage [R, R].

NAC (1,200 mg/day) protected 48 textile-industry workers from hearing loss after 2 weeks (RCT) [R].

But in one study (DB-RCT), NAC taken before listening to loud live music in a nightclub for 2 hours had no protective effect in 31 people[R].

NAC could also help with ear inflammation. In 90 children with middle ear inflammation, NAC alone (300 mg/day) or combined with antibiotics improved symptoms. It had a stronger effect combined with the antibiotic [R].

17) NAC May Improve Autism

NAC seems to have some benefits for children with autism, but these are still uncertain.

NAC alone (900-2,700 mg/day) could reduce irritability in a study of 33 children with autism (DB-RCT) after 3 months [R].

In 2 studies with 80 autistic children (RCTs), those who got NAC as an add-on to an antipsychotic (risperidone) had less irritability and hyperactivity after 2 about months [R, R].

But NAC had no benefits in children with autism in one study (RCT) [R].

In another, it could boost glutathione in 31 children with autism (DB-RCT), but had no effect on their social functioning [R].

18) NAC Helps with Dry Eyes

Just one application of NAC eye drops helped improve dry eye symptoms in a study of 38 people (DB-RCT). The eye drops contained NAC bound to chitosan (as chitosan-NAC) [R].

A 5% NAC cream worked as well as the typical steroid cream in a study of 20 people with dry eye syndrome (RCT). It improved burning, itching, and blurry vision after a month. It was also much more effective than artificial tears in another study of 20 people with dry eye syndrome [R, R].

19) NAC Reduces Muscle Fatigue

The effects of NAC on exercise are not that straightforward. Overall, NAC tends to help muscles recover shortly after exercise and improve blood flow during intense exercise. It also seems to help elderly people improve their fitness and enhances endurance in athletes short-term. However, long-term NAC with exercise may prevent muscle recovery.

In Athletes

In one study NAC supplementation (1,200 mg/day) improved demanding cycling performance in 10 athletes after 9 days. It increased their antioxidant capacity, physical performance, and muscle recovery [R].

But in one study of 80 men, NAC taken before exercise didn’t increase endurance or muscle blood flow [R].

One study concluded that NAC can alter the energy balance in muscles and hinder muscle repair. When given to 10 men after intense exercise (DB-RCT), it lowered inflammation in the muscles but at the same time slowed down muscle recovery after 8 days [R].

And in another, NAC worsened performance and decreased power output during HIIT training in 9 athletes [R].

In one study of 12 men, NAC improved exercise performance after 6 days during which they trained every other day. Overall, NAC may help in these situations that demand continuous intense exercise only over a short period of time [R].

Muscle Fatigue and Inflammation

In several studies of 16 people in total, NAC infusions (1,800 mg) given before intense exercise reduced post-exercise muscle fatigue [R, R].

NAC could help maintain high levels of the anti-inflammatory IL-10 even a week after exercising in 29 people [R].

Power Training

NAC could reduce muscle fatigue in exercises that demanded only 80% muscle power, while it wasn’t beneficial for high-power training (higher muscle work rates) in 7 men [R].

NAC increased glutathione and blood cysteine in several studies in healthy people, which was linked to improved strength, endurance, and exercise performance [R, R].

Inactive or Elderly People

NAC could also speed up muscle repair in a study of 29 sedentary men (RCT). They took 1,200 mg of NAC daily for a week before exercising. NAC increased their antioxidant and muscle blood flow [R].

NAC also increased muscle strength in older people (DB-CT), whose antioxidant levels are low. It also reduced TNF-alpha, an inflammatory marker [R].

20) NAC Reduces Antibiotic Side Effects

Antibiotic side effects can arise from free radicals damage. As a strong antioxidant, NAC (1,200 mg/day) reduced side effects, prevented kidney and ear damage from several strong antibiotics in 2 studies of 100 people (RCTs) [R, R].

NAC could also protect the liver from the harmful effects of anti-tuberculosis drugs in a study of 60 people (RCT). Those who took NAC had intact livers after treatment, while 40% of those who didn’t take NAC suffered liver damage [R].

21) NAC Is Beneficial for Red Blood Cells and Bleeding

In 61 people with thalassemia, an “antioxidant cocktail”, containing NAC with curcuminoids or vitamin E, improved anemia and hemoglobin levels after 4 months. NAC had similar benefits in 75 children with thalassemia, while also reducing DNA damage [R].

NAC (1,200-2,400 mg/day)  improved blood markers and antioxidant levels in 11 people with sickle cell anemia [R].

NAC combined with oxygen increased erythropoietin production in 38 healthy people, which would also be beneficial for those with anemia [R].

Additionally, NAC (1,800 mg/day) reduced the severity and frequency of bleeding in 43 people with a bleeding genetic disorder. This benefit was also linked to its antioxidant power [R].

Weaker Benefits

1) Pain and Inflammation

NAC is anti-inflammatory. In cells, it could target the same pathway as common anti-inflammatory painkillers (COX-2) [R].

NAC could alleviate complex pain in a study of 146 people over 2 years (DB-RCT), especially in those with poor circulation. The participants took 1,200 mg NAC daily [R].

NAC reduced neuropathic pain in rats by blocking an important inflammatory pathway (matrix metalloproteinases) [R].

NAC (1,200 mg/day) reduced inflammatory markers such as CRP and IL-6 in a study of 24 people with kidney disease. Given to 15 patients with severe burns, NAC reduced oxidative damage, increased antioxidant protection, and reduced inflammatory markers [R, R].

But it had no effect on kidney inflammation in kids nor on leg cramps (RCT) [R, R].

2) Insulin Resistance and Type 2 Diabetes

NAC can target insulin resistance thanks to its capacity to restore antioxidant levels and reduce oxidative stress. Plus, people with type 2 diabetes may have lower glutathione levels that NAC can replenish [R].

In one study, 14 people with type 2 diabetes took 1,200 mg of NAC every day for a week and had their blood drawn shortly after (RCT). NAC increases glutathione in platelets and normalized their activity, which could protect from heart disease in type 2 diabetes [R].

When glutathione is added to white blood cells of people with type 2 diabetes, it restores their immune and bacteria-fighting function. Since NAC increases glutathione throughout the body, it

may be helpful for restoring antioxidant balance in people with diabetes [R].

When given to 128 people before a high-fat meal, NAC could help maintain antioxidants and blood vessel health. It reversed oxidative stress, which was very noticeable in people with type 2 diabetes and insulin resistance. Since the group was medication-naive, NAC may delay or prevent the need for anti-diabetes drugs in type 2 diabetes [R].

Animal studies speak to its benefits too. NAC prevented mice fed a high-fat diet from gaining excessive weight and symptoms of insulin resistance [R].

NAC does not affect type 1 diabetes, though, as factors aside from oxidative stress play a large role [R].

3) Alzheimer’s Disease

An antioxidant supplement containing NAC improved cognition and mood in 130 people with Alzheimer’s disease 2 studies (open-label and DB-RCT) [R]. Participants took the supplement for up to one year.

In one trial, NAC alone also improved all symptoms of Alzheimer’s Disease after 3-6 months (DB-RCT) [R].

In mice with Alzheimer’s Disease, NAC prevented brain damage, memory, and cognitive decline. It could restore normal acetylcholine signaling and energy use in the brain [R].

4) Parkinson’s Disease

NAC may protect the brain in people with Parkinson’s Disease. In one study, people with Parkinson’s Disease took NAC for 3 months and then underwent brain scans. NCA improved the activity of their dopamine neurons, which are incredibly important in this disease [R].

New brain scanning techniques can now measure levels of the antioxidant glutathione in the brain, which could help guide and track treatment outcomes. NAC increased glutathione levels in the brain in 3 people with Parkinson’s Disease [R].

5) Schizophrenia

NAC may help improve symptoms of schizophrenia and psychosis by balancing the brain’s glutamate levels, fighting oxidative stress and inflammation.

NAC improved cognition and working memory in 58 people with psychosis (DB-RCT), taken at a higher dose of 2g/day. It also reduced symptoms like mania and hallucinations as well as improved response to standard treatment in another study of 121 people [R].

Combined with antipsychotics, NAC improved overall symptoms in 42 people with schizophrenia with no side effects (DB-RCT). It especially helped with low mood and apathy [R].

This may be because NAC helps the brain waves become more synchronized. One EEG study (DB-RCT) in people with schizophrenia showed that this synchronous brain wave activity can predict improvements [R].

Overall, NAC benefits schizophrenia based on the clinical trials so far [R].

And other clinical studies are currently underway that will soon tell us more [R].

NAC could also reverse the risk of schizophrenia in genetically predisposed mice by normalizing brain connections [R].

6) Heart Disease

Oxidative damage is one of the underlying causes of heart disease. NAC prevented mice with diabetes from developing heart complications [R].

NAC also reduced heart damage in rats with chronic heart failure, while also improving fatigue and exercise tolerance [R].

In almost 100 patients who had heart attacks, NAC sped up recovery short-term. Long-term, it could improve heart health and reduce complications (RCT) [R].

Serious heart arrhythmias are also linked to oxidative stress. In blood taken from patients, those who took NAC aside from drugs used to treat arrhythmias had higher antioxidants and reduced inflammation [R].

7) Bone Health

In 21 women who recently went through menopause (DB-RCT), NAC strengthened the bones and their density when added to a vitamin D and calcium supplement regimen. It was used safely over 3 months [R].

In rats, NAC enhanced bone growth, mineralization, and regeneration while also boosting collagen [R, R].

8) Ulcers and H. Pylori

H.pylori is the most common cause of ulcers. NAC somewhat enhanced the effects of H.Pylori treatment in one study of under 100 people (RCT). In another of 60 people (DB-RCT), it helped antibiotics penetrate to the site of infection [R, R].

NAC may play a role in overcoming antibiotic resistance by destroying biofilms. NAC increased the sensitivity of H.Pylori to antibiotics by disrupting biofilms in a study of 40 people. It could be given before antibiotics to boost their effect [R].

9) ALS

Oxidative stress plays a role in developing diseases like ALS. NAC offers some hope for ALS patients. But so far, it was only shown to prevent ALS-like degeneration of brain cells  [R].

10) NAC May Protect the Gut and Reverse SIBO

As a powerful antioxidant, NAC can help protect the gut and reduce small intestinal bacterial overgrowth (SIBO).

Gastric reflux, or heartburn, is alarmingly common. In 90 people with gastric reflux (GERD), NAC improved most symptoms after 3 months given as an add-on to standard PPI drugs [R].

But these medications, PPIs, can often cause small bacterial overgrowth, as they reduce the gut’s pH making it more hospitable for bacteria. One study of 30 people confirmed this, as well as that several strains of antibiotics combined with NAC can reverse the condition. Once reversed, NAC and probiotics restored the gut barrier and prevented SIBO in the long run [R].

NAC also reduced gut inflammation In 37 people with colitis (RCT), helping to reduce inflammatory substances like IL-8 [R].

In rats, it could also reduce leaky gut, helping to strengthen the intestinal barrier and boost antioxidant defense [R].

11) Cognition

Combinations of NAC with other antioxidants improved cognition in both healthy older people and in those with mild cognitive impairment [R, R]

NAC has already been researched for improving cognitive function in Alzheimer’s, Parkinson’s, and schizophrenia. It is also currently being researched for boosting cognitive performance after general anesthesia [R].

12) Brain and Spine Injuries

NAC may act help recover from brain trauma or reduce the damage from various stressors in the brain by combating free radicals [R].

It could reduce the effects of traumatic brain injuries even during combat, according to a study of 81 U.S. soldiers (DB-RCT) [R].

NAC can cross the blood-brain barrier in children with traumatic brain injuries without side effects (DB-RCT) [R].

It could also increase antioxidants and helped protect the brains of children with a deadly, rare brain disease [R].

In pregnant women, NAC could protect their fetuses from the complications of vaginal infections on the brain (DB-RCT) [R].

In rats, NAC could protect from spinal trauma and protect energy balance in the cells. It also reduced the damage from TBIs in rats [R, R].

13) Kidney Disease

Oxidative stress can cause kidney failure in the most severe cases. It was first shown that NAC can protect the kidneys from damage in rats [R].

Since then, at least 30 clinical studies have looked at the protective effects on NAC in kidney injury, before or after kidney or heart surgery, as well as when it comes to thyroid problems in kidney disease. Most of the studies have shown positive results, which brings NAC into hospitals as a potential treatment for severe cases of kidney and lung disease [R, R, R, R, R, R, R, R, R, R, R, R, R, R].

When used in serious diseases and to reduce organ damage, NAC is usually given as an infusion or injection.

14) ADHD

NAC reduced ADHD symptoms in patients with lupus in a study of almost 100 people. NAC improved cognition, impulsivity, and overall symptoms given at up to almost 5 g/day [R].

15) Cancer

NAC could fight some cancers in cellular and tissue studies [R, R, R].

NAC could also protect animals from radiation, protecting the DNA by its antioxidant capacity [R].

No clinical studies proved any cancer-fighting benefits yet.

Only in one study of 25 women who had cancer and were in remission, NAC could help rebalance female hormone levels [R].

16) HIV

People with HIV tend to have lower antioxidant and glutathione levels.  In one study, 1 g of NAC per day was enough to bring glutathione levels up in 12 people with HIV after only a week. In another 6-month study, those who took 600 mg NAC/day also reduced the HIV virus number and activity while boosting the immune response [R, R, R].

NAC could boost the activity of macrophages and glutathione levels in people with HIV and tuberculosis, which helps fight off the infections [R].

Higher glutathione levels from NAC could prevent the HIV virus from replicating in cells [R].

17) NAC May Protect the Gums

NAC improved gum bleeding in a study of 33 people with gum disease after surgery [R].

18) NAC May Help with Mountain Sickness

NAC somewhat helped with mountain sickness in one study in 84 people living in very high altitudes in Peru (over 4000m). It did not work better than the standard drug, acetazolamide, though (RCT) [R].

19) NAC May Improve Cystic Fibrosis

NAC reduced inflammation and increased antioxidants in 18 women with cystic fibrosis who were deficient in glutathione [R].

The short-term effects are not that evident, but long-term NAC use may be more beneficial (SR) [R].

20) NAC and Pregnancy

There is not enough research to claim whether NAC is safe in pregnancy, so we don’t advise that you take it if you are pregnant without consulting a doctor first.

Several studies show some benefits of NAC for pregnant women or their babies.

NAC helped reduce unexplained pregnancy loss in 80 women. A combination of NAC and folic acid was used  [R].

NAC could protect the fetus from brain injury caused by the mother’s bacterial infection [R].

In 29 pregnant women low antioxidant status (DB-RCT), NAC in combination with other antioxidants improved pregnancy outcomes [R].

It also helped prevent preterm births in 280 women with vaginal infections [R].

These studies mostly used 600 mg/day of NAC.

21) NAC in Irritable Children

NAC reduced obsessive skin picking in a study of 66 children with the disorder (DB-RCT). Children took NAC for 3 months, up to 3 g/day, and tolerated it well [R].

It could also reduce compulsive nail biting in 42 children at 800 mg/day [R].

It seems to help only with obsessive or compulsive behaviors. But NAC did not improve tic symptoms in 31 children with Tourette Syndrome [R].

22) NAC in Emergency Medicine

NAC has been studied a lot in the intensive care units, as a possible way to reduce organ damage before and after surgery. It helped protect the liver in 70 patients with lung disease, given shortly before heart surgery. 900 mg/day of NAC was given for a week [R].

NAC also reduced liver damage when given shortly before liver surgery in a study of 48 people (DB-RCT) [R].

It could help with heart attack complications, assisted breathing, abdominal surgery, and pancreatitis when used in the emergency case, before or after surgery [R, R, R, R].

NAC Side Effects & Caution

NAC seems to be a safe substance with very few known side effects.

Occasionally, oral supplements can cause nausea, vomiting, diarrhea, or constipation.

Because of the sulfur-containing cysteine, NAC does smell bad (sulfur smells like rotten eggs), which makes the powder form unappealing for most people.

People with severe liver damage can’t make GSH from cysteine an may need to take a bioavailable form of GSH itself [R]

Since NAC can impact the platelets and reduce coagulation[R], take precaution or consult your doctor if you:

  • Have a bleeding disorder
  • Are having surgery soon, because of an increased risk of bleeding during and after surgery.
  • Take blood-thinning medication, as in combination with NAC the effect may be stronger

In rats, very high doses of NAC (12 mg/kg/day) increased blood-brain barrier breakdown and blood vessel injuries. These effects were not shown in clinical trials [R, R].

NAC Dosage

800-2,400mg of NAC was very common across clinical studies. If you have a chronic health condition, you can consider taking a higher dose. The daily doses are usually divided into 2-3 times per day.

Some studies the benefits of NAC for reducing addiction and mental health issues used doses closer to 3000 mg/day.

For general wellness or gut health, 600 mg a day is the typical dose.

A maximum safe dose of NAC has yet to be determined.

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The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.

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49 COMMENTS

  • Robyn Quinn-Hakeem

    I just need to double check that this isn’t good for someone with very high blood pressure??? My hubby has many issues with that being one but this could help ALL OF HIS PROBLEMS according to this article…

  • Marie

    I’m getting this for my husband and his friend does anyone know if it does help with addition to ice.. my husband needs some type of help an im.starrimg with this any ideas. Thank you

    1. VoteNov6

      Here, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3044191/, are references to studies that showed NAC being used effectively in treating cocaine addiction.

  • Maggie

    Can anyone recommend what dosage to take? I have it in crystal form

  • Joan

    I’ve been taking NAC twice per day recommended by my naturopth. However, it has made my urine very light in color and in the morning my first urine is crystal clear no color. I am worried that my kidneys are not filtering right. Does anyone know why this would be happening? I am certain it has something to do with N A C as I did not experience this before.

  • Darren

    Hi can anyone give me more information and there experiences about taking nac for gambling addiction? thankyou

  • Jerry

    Has anyone with Muscular Dystrophy taken? If so how did it affect you?

  • claude roy

    would NAC help my COPD

  • Barbara

    I took my first NAC 600mg pill right after breakfast and WOW did I get a buzz. Heart was doing a happy dance, short of breath. Scared the bejesus out of me. What might the problem be?????

  • linda

    i am allergic to penicillin and sulfer. Can I take NAC

  • Brian Kerner

    Will NAC help alleviate the pain and discomfort in severe Neuropathy in the feet?

    1. Fae

      Not sure, seems like it wouldn’t hurt to try! Look into magnesium malate for neuropathy.

  • Rob Allen

    I am pain free first time in 30 years I have severe back
    pain (all gone) blood pressure lower cough gone depression
    gone anxiety gone OCD gone all addictions gone

    I now feel that the medical community lied about what
    medicine they said I needed went to doctor today he
    could not believe my numbers from blood pressure to kidney liver every number from my blood work was perfect and
    when I told him I was on no meds he just shook his head
    I’m 62 and before this I was headed down heel super stiff
    back high sugar blood pressure out of wack blood numbers
    all of my conditions are gone one plus year now no side effects
    I take 600 twice a day it’s a miracle and lately I feel way
    younger I can now run up 10 flights of stairs at full speed
    I can ride a bike again jog my sex life way better this supplement
    has completely changed my life!!

  • Upasana

    Is n acetyl helpful in treating brain fog and what is the dosage to be taken , for how long?

  • Håkon Martin NIlsen Bjerke

    I dont have any problems with upset stomach from NAC myself, just try and see before looking for other solutions..

  • Cathia

    Thanks for covering this. Would you please update to include details about NAS and endometriosis (example: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3662115/)? Thanks again.

    1. Fae

      Yes!!! NAC just saved me from having to get emergency surgery for endometriosis related cysts on my ovaries!!! Everyone should know about this!

  • Carolyn Miller

    Is it gluten free

  • Rob

    Agreed: it’s the first thing I take if I come down with any chest congestion; it helps move it up into my head, which is easier to treat than the chest area.

  • Cathrin Leth

    If it can upset the stomach so much, would it be possible to put it in a bit of water or oil, to dissolve it, and put it on the skin for absorbtion?

  • higgledie piggledie

    Wow – great detailed informative comment from Matthew with some concerns on the downsides.
    Can we get Joseph to go through this and other concerns raised and provide a detailed response on if these concerns are valid, if not why not, and if so how to manage them?
    To me the value of coming to a site like this would be to address these questions in an informative manner……

  • Dr. Mike

    While I agree, I found that once inflammation is running amok, as with many chronic diseases like my RA, I can take 500 mg a day of it with no negative problems. In fact I take a massive cocktail of OTC products like NAC that saved my life the last 3 years. My RA factor is not measurable. Only issue I had to address was to cut to back anything that reduced blood clotting or thins my blood. That was a fascinating google search and iterative process for me. Many (most?) of the anti inflammation products, even some common foods also act as mild blood thinners, which is bad if you bruise or leak hemoglobin easily through the capillaries or have leaky gut (Like I did)!!! Ever looked at Fentons reagent (Iron) use as a free radical initiator? As in iron from Hemoglobin leaking into joints and muscles!!!

  • Dr. Mike

    Awesome comments, I have been taking 500 mg/day for about 2+ years. I am thinking of doubling the dose, 12 hours apart now after getting back up to speed on what all it does. Fighting just RA now (RA factor is off the charts), but was fighting 5 illness at once 3 years ago, Hyperthyroid, Bronchitis from hell, Off the charts lab test for RA, lost 80 lbs in 12 weeks, could barely move, every muscle in my body was on fire, bruised easily, Gall bladder stones from hell, and all sorts of blood and liver numbers out of whack. This was, is one of about 30 supplements that got me back on my feet, in my 60s. It has never given me any problems. But every person and their health, and issues are unique! I also take l-Glutamine, a lot of it!!!

  • Matthew

    I’m really not sure about NAC. The creation of reactive oxygen species (ROS), often portrayed as bad and one of the reasons why we need plenty of antioxidants, is a crucial biochemical stressor that upregulates autophagy and induces apoptosis, an important process in cancer and many chronic diseases. Indeed, many of the benefits conferred by nutraceuticals that inhibit TOR and activate AMPK do so, in part, through ROS-mediated mechanisms. NAC certainly, as well as concentrated doses of vitamin E I believe, has the unfortunate effect of negating these effects due to extremely potent scavenging abilities.

    That said, excessive ROS isn’t good either so obviously a balance needs to be struck. Personally, if NAC was to be used it would seem prudent to take it away from nutraceuticals who’s benefits come, at least in part, through such ROS-mediated mechanisms. Indeed, the remark in the article on taking it every other day seems a good one as you would be mopping up ROS to keep levels in check but not overly inhibiting key processes on a daily basis.

    Personally, I try to focus on optimising methylation to ensure the endogenous synthesis of cysteine is what it should be, along a raft of other benefits. I like to think that if that system is working correctly then the body will be able to make its own glutathione in the correct amounts as and when it needs to. Incidentally, on this remark, it’s interesting to note that high inflammation levels as brought on by disease has been shown to cause significant tissue-specifc depletion in such things as vitamin B6. Of course, such depletion could handicap methylation, inhibit glutathione synthesis and further immune dysfunction as a result. So maybe B vitamins, especially in active forms, along with some other cofactors are necessary in greater amounts during times of significant inflammation to bring this system in to balance.

  • Betty

    Has anyone with MS taken NAC and had good results ? I would love to hear back from you.

  • Philip Blake

    It’s 50/50. It can also cause diarrea.

  • Lacey

    Prune concentrate, helps my son. It’s natural and very effective. Play w the doce. It’s thick and highly concentrated. Helps with my son a lot.

  • Anne Doney

    I have constipation from codeine. I intend to reduce the codeine. I understand that NAC encourages constipation. Is this true? How can I get the benefits of NAC without constipation?

  • argo

    You’ve to be careful about the excipients added to commercial brand of NAC: for example toxic sweeteners as aspartame are often included.

  • Erin Price

    It was my understanding that is mobilizes mercury out of storage and it circulates to brain and causes mercury toxicity symptoms.

  • Erin Price

    I became convinced it was mobilizing mercury (in my body leached from dental amalgam). Perhaps that was not the cause but I felt dizzy foggy nauseous tired…just gross. Had to stop it

  • An-Marie

    N-acetyl-cysteine attenuates neuropathic pain by suppressing matrix metalloproteinases : https://www.ncbi.nlm.nih.gov/pubmed/27075430?dopt=Abstract

  • Nejc

    NAC and alpha lipic acid do cause autoimmune insulin syndrome in genetically prone people. Please add in cons.

  • Ericsson Williams

    Hello, I experienced intestinal issues for a few days but it went away. I take Jarrow Sustain 600mg NAC, and I take my dose mid-day. I don’t eat for a few hours after my dose. It says to take it on a empty stomach but I don’t like to take anything on a empty stomach.

    Wishing you the best,
    EW

  • Marcela

    Following Dr Hahns infectious asthma protocol, I was able to eliminate my asthma attacks, dpendency on inhaled glucocorticoids in 2011. NAC was invaluable during this time while dealing with a herx reaction. I don’t take it daily, but if I feel my chest tightening or a cold coming, it’s my go to supplement.

  • Michael (NW)

    Hi, I started taking N-A-C @ 500mg before bed to help with sleep. It seems to help. But… I’m trying to figure out why I have IBS like symptoms such as very soft stools with cramping in the mornings. I tend to have that every now and then but it’s almost every morning now. I wonder if it’s the N-A-C? If it is, is there a way to negate these effects? Is there a liposomal formal of NAC? I wouldn’t think a enteric coated version would help in this case. I believe NAC is helping with my insomnia (maybe lowering glutamate?) and with moods and inflammation so I’d hate to stop but the daily bowel issues is not good. I do have some other digestive issues and have been experimenting with Ox Bile, Betaine HCL, and Pancreatin. But, before going on NAC regularly and increasing my dose to 500MG I wasn’t having as many bowel issues like this. Anyway can a 500mg dose of NAC cause bowel issues?

  • Rosa

    I`ve heard interview with Dr. Mark Hayman, in which he said that NAC taken at the time of antibiotics treatment protecs mitochondria from damage. Any ideas about the dosage and timing (togeter with antibiotics or several hours away from it)?

  • An-Marie

    Is it true that NAC, if someone has mercury or other heavy metals in their body, it can actually drive the mercury deeper into the tissues and the brain if it’s used too early in a detoxification process, such as in a compromised gut ?

  • jamesbiehl

    I believe that NAC can raise histamine. It also may have some negative effects over 500mg. You can find more information, but here is a darn Mercola article (below). I believe it can also cause problems by chelating heavy metals.. Perhaps a good idea to also take some chlorella with the NAC, and keep the dose between 200-500mg once per day with breakfast.. I remember reading about a study people had on Longecity about the damage NAC could impose over 500mg. No link for that at the moment.

    Here is another study about long term low dose negative effects:
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3913600/

  • anna burns

    I was considering supplementing with NAC, but when I began to look into it I saw that the supplements frequently oxidize. I would appreciate comments on this. I would like the benefits of
    NAC, but not if it is oxidized.

    1. Joseph M. Cohen

      I don’t think so

  • Jason West

    Bipolar depression and Major Depressive Disorder are very different illnesses. You should cite the Bipolar studies also, not only Major Depressive Disorder studies.

  • Ted Hu

    Does nac increase cysteine and up taurine vs glutathione for those with homozygous cbs A360A mutation? Or will it as one paper suggests curb thiol and cysteine levels.

  • Donita

    I believe NAC caused brain fog. About 4 – 6 weeks after starting it, daily with 16 oz of water, then breakfast, and substantial water all day, I started to feel sluggish, and about 3-4 days of that, I tried to tackle a common activity (genealogy research), and was confused and unable to proceed. I quit the NAC for several days, then started again, taking only 1 pill (250 mg I think) ONCE a week with evening meal. I may be receiving little or no benefit with such a low dose, but am continuing at this rate until I learn more.

    1. Astral Pharoh

      That’s because NAC lowers Glutamate. Glutamate is your main energizing neurotransmitter. With lower levels of Glutamate, your CNS is more sluggish. It does the same thing to me. It lowers Glutamate by converting it into glutathione…

      1. Adam Rankin

        I’ve read reviews where customers felt like they were thinking clearer and had more energy. So I’m wondering if they had to much Glutamate to begin with?

    2. Ann

      I used to feel the same in addition to feeling toxic and getting bad headaches until I started taking 200mcg selenium & Molybdenum with it!!
      All disappeared!
      Good luck

  • anna burns

    I know the benefits of NAC, and have tried several times to take it, but it makes me feel so bad, that I had to stop. Any ideas as to why that might be?

    1. Ted Hu

      I suspect if one has cbs mutation nac raises cysteine and taurine levels and with it sulfate and ammonia. While it helps mutate glutamate receptor excitability, it does not curb unregulated cbs enzymated transulfurstion pathway.

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